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My table name students
uid | name
-----+-------
10 | John
11 | Smith
**Data types : **
uid int(11)
name varchar(256)
My query :
SELECT name FROM students WHERE uid = '10'
Returns : John
My 2nd query :
SELECT name FROM students WHERE uid = '10someChar'
Returns : John
Why the second query returns John ?
593
12 years, 10 months ago. it's for php to know how to handle the parameters, %d – the argument is treated as an integer, and presented as a (signed) decimal number. %s – the argument is treated as and presented as a string. in your examples, $slug is a string and $this->id is an integer.
Syntax to check if the value is an integer. select yourColumnName from yourTableName where yourColumnName REGEXP '^-?[0-9]+$'; The query wherein we have used regular expression. This will output only the integer value.
The syntax for assigning a value to a SQL variable within a SELECT query is @ var_name := value , where var_name is the variable name and value is a value that you're retrieving. The variable may be used in subsequent queries wherever an expression is allowed, such as in a WHERE clause or in an INSERT statement.
The uid column is integer, and the value you pass in the where clause is first coerced into an integer... and most integer-conversion algorithms just grab the first set of digits they can find in the string (and ignore anything non-matching after it)... thus it finds 10 and ignores the rest
111
MySQL automatically converts numbers to strings as necessary, and vice versa.
It is also possible to convert a number to a string explicitly using the CAST() function.
Type Conversion
take a read.
MySQL ever tries to return something - even if it's the wrong type, he'll cast automatically.
You should filter at PHP to validate your business rule.
Postgresql should throw a exception
25
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